1) detect/mark cycles in the ugen graph when changing connections 2) when computing samples, nodes in cycles still compute sample at a time, while the rest can compute in blocks. 3) furthermore, non-cyclic nodes need to be partitioned and sorted. subgraphs that a cycle depend on must compute the block before the first sample of that cycle computes. 4) We may be able to further optimize if delay-lines are involved in the cycle.
<thinking hat off for a sec...> Interesting problem. I thought it was trivial until I realized that there may be multiple loops with multiple minimum block sizes. However, it may be trivially doable after a little non-trivial thinking. I was going to ask whether circular chucks was a feature you were particularly attached to, when I saw somebody posting about the fun they were having with delays and echos. And then, in a blinding flash of insight, I understood why the Stk Echo doesn't have a feeback property. (echo echo echo echo). <... thinking hat back on> - Robin Davies.